The present invention relates to a new and improved apparatus for dispensing individual plastic fasteners from continuously connected ladder stock.
Plastic fasteners of the type having, for example, a T-bar at one end, a paddle at the other end, and a thin filament or cross-link connecting the two ends, are widely used in commerce to attach labels or other items to articles in a manner which minimizes the risk of inadvertent detachment therefrom. Typically, such plastic fasteners are manufactured in the form of fastener stock, a multi-unit assemblage of fasteners produced by molding or stamping from flexible plastic materials, such as nylon, polyethylene, and polypropylene. One type of fastener stock, referred to as continuously connected ladder stock (or, more specifically, as continuously molded ladder stock), typically comprises a pair of elongated side members interconnected by a plurality of cross links or filaments. Typically, one side member is shaped to define a plurality of co-planar T-bars which are joined together by short severable connectors, the connectors being defined by indentations or notches formed along the side member.
Additional information pertaining to fastener stock in general or to continuously connected ladder stock in particular may be obtained from the following commonly assigned U.S. patents, all of which are incorporated herein by reference: U.S. Pat. No. 4,955,475, issued Sep. 11, 1990; U.S. Pat. No. 4,456,161, issued Jun. 26, 1984; U.S. Pat. No. 4,121,487, issued Oct. 24, 1978; and U.S. Pat. No. 3,103,666, issued Sep. 17, 1963.
The dispensing of individual fasteners from fastener stock into desired articles of commerce is typically accomplished with an apparatus commonly referred to as a "tagger gun." Typically, a tagger gun includes a mechanism for cutting an individual fastener from the fastener stock and a mechanism for feeding the individual fastener through a needle at the front end of the tagger gun so that it may be inserted into the desired article of commerce.
In the commonly assigned U.S. Pat. No. 5,024,365, which issued Jun. 18, 1991 and which is herein incorporated by reference, an improved system for dispensing a fastener through a slotted hollow needle from continuously connected ladder stock is described. The system includes an actuator slide with a central channel, such actuator slide being secured to the ejector rod and fastener stock feed mechanism to actuate these functions. The system further includes a shuttle assembly which reciprocates transversely to the needle axis to cause the cutting of a fastener from the ladder stock, and transport of the severed fastener to the needle axis . The cam bar is linked to the shuttle mechanism and pivotally mounted so that the pivoting of the cam bar causes the transverse shuttle motion. The cam bar passes through the actuator slide channel, whereby sliding of the actuator slide causes pivoting of the cam bar according to the profile of the cam. The apparatus, which is trigger-operated, further includes an antiback mechanism in the form of a catch lever which engages the trigger when it has been partially depressed and prevents its release, until the trigger has been fully depressed.
In the commonly assigned U.S. Pat. No. 4,456,161, which issued Jun. 26, 1984, an apparatus for dispensing fasteners is described. The apparatus comprises a casing, a dispensing hollow slotted needle mounted on the casing, means for advancing a fastener to a position adjacent the rear of the needle bore with its end-bar transversely disposed to the longitudinal axis of the bore, means for aligning the end-bar with the needle bore, and means for dispensing the end-bar through the bore. Preferably, the apparatus comprises a feed wheel, an aligning means comprising a reciprocating cam slide which also actuates the feed wheel, a dispensing means comprising a plunger carried by a reciprocating support which also actuates the cam slide, and means for reciprocating the support.
Additional types of tagger guns are described in the commonly assigned U.S. Pat. Nos. 4,121,487 and 3,103,666, which are referred to above.
Applicants have recognized that one disadvantage with tagger guns of the type described above is that such tagger guns are typically designed so that an individual fastener is cut from the fastener stock prior to its being loaded into the needle mounted at the front end of the tagger gun. This sequence of events occasionally results in jamming of the tagger gun as the severed fastener, which may possess slight deformities as a result of the cutting step, must be transported from the cutting station to the needle and then loaded into the needle for dispensing.
Applicants have also recognized that tagger guns of the type described above occasionally experience losses in accuracy and control during the feeding, cutting, and/or ejecting steps. These losses in accuracy and control, which may result in jamming of the tagger gun, appear to be attributable to use of the cross link or "filament" portion of the fastener to position the fastener during the feeding, cutting, and/or ejecting steps.